Grate



April 28, 1931-.

J. S. THOMPSON GRATE Filed Nov 12, 1929 ATTORNEYS Patented Apr. 28, 1931 JAMES S. THOMPSON, OENEW YORK, N. Y.,

PATENT OFFICE ASSIGNOR TO FIREBAR CORPORATION, OF

CLEVELAND, OHIO, A CORPORATION OF DELAWARE GRATE Application filed November 12, 1929. Serial No. 406,558.

' This invention relates. to fuel grates and is concerned more particularly with a grate bar of'novel construction especially adapted for use in boiler furnaces, locomotive fire boxes 55 and like structures.

The grate bar of the invention is constructed to provide a wide distribution of the air used for combustion to all parts of the fuel bed supported on the bar. To this end,

the bar is provided with 'a multiplicity of separated fuel-supporting areas of small dimensions so that only a small proportion of the bottom surface of the layer of fuel is in actual contact with a solid surface of the bar and the dead spaces in the bottom of the fuel bed are thus reduced to a minimum consistent with proper support. In order to insure that the air flowing through the bar from the ash pit to the fuel will not be concentrated and delivered to certain localized areas, as is thecase with present bars, the new bar is provided with air passages through it of constantly decreasing cross-see tional area from bottom to, top of the bar.

The upper ends of these passages where the constrictlon is greatest are in effect orlfices through which the air flows to the fuel, and

at these orifices there is a substantial pressure drop which is utilized to accomplish horizon-- tal distribution of the air.

The fuel-supporting surface of the bar is subdivided, by air channels which extend substantially horizontally and these channels communicate with the air passages below the point of maximum constriction thereof, so that as the air flows up throughthe bar, it reaches the ends of the channels just before it reaches the main orifices, and there is an effective pressure drop in the channels which results in the air flowing along the channels and laterally across the upper surface of the bar. The constriction of the passages above the bottom of the channels further promotes the lateral flow, since it offers resistance to the direct upward flow of air through the passages beyond the ends of the channels. In the improved construction, therefore, wide horizontal flow and distribution of the air to all parts of the under surface of the fuel bed are obtained with efliciency.

Due to the fact that the bottoms of the channels are formed with a slight upward inclination away from the air passages,'ashes which collect in the channels tend to slide down the channels to the passages and fall improved combustion through the latter to the ash pit. Also, since each fuel-supporting area on the grate is relatively small and air flows around it on all sides, the grate is protected against burning out and has a much longer life than former grate bars in which the dead spaces form a substantial part of the total area of the bars.

For a better understanding of the invention, reference may be had to the accom-" panying drawings, in which Frg. 1 1s a transverse section through one .of the grate bars of this invention showing a fuel-supporting unit in side elevation;

Fig. 2 is a fragmentary plan view thereof; Figs. 3, 4, 5, and 6 are sectional views on the lines 33, 4-4, 55, and 6 6,respecti-vely, of Fig. 2; and

Fig. 7 is asectional View on the line 7-7 of Fig. 1.

Referring now to the drawings, the bar is illustrated as consisting of a longitudinal supporting member 10 having an upwardly extending flange 11, a plurality of cross-bars 12 being supported loosely on member 10.

The supporting member is provided at each end with a trunnion 13 and has a downwardly extending shaker arm 14 by which it can be connected to a shaker rod in the usual manner. Each supporting member carries a plurality of the cross-bars loosely mounted thereonand readily removable from the supporting member in an upward direction. The

provision of cross-bars loosely mounted on a supporting member forms no part of my invention, but is set forth and described in .a co-pending application of Buckley, Serial No. 338,352, filed February 8, 1929. The features of grate bar construction which constitute my invention may be incorporated ina bar of the Buckley type in which the cross-bars are removable from the supporting member or may be employed in a grate bar in which the cross-bars and supporting membervare formed as an integral unit.

Each cross-bar extends laterally with respect to the supporting member for a substantial distance and the cross-bar includes a plate-like body 15, which is of gradually increasing thickness from the lower edge 16 to the top 17 On each face of the cross-bar is a series of lugs 18 extending downwardly a substantial distance from the top thereof. These lugs increase in'width from their lower end 19 to the top 20 and also increase in thick- -ness, as illustrated more clearly in Fig. 4.

The distance between the opposed sides of adjacent lugs at their lower ends is thus substantially greater than the distance between these sides at the upper ends of the lugs. The cross-bars lie-side by side on the supporting member and are kept in the desired spaced relation by spacing projections '21 formed as a part of the lugs 18. There is a pair of projections on each side of the crossbar and the projections on adjacent crossbars contact, as illustrated in Fig. 7 as to provide the proper spacing between the crossbars on the supporting member. When the cross-bars and supporting member are formed integrally, the spacing projections areomitted. A

Formed in the upper surface of the platelike body of the cross-bar is a longitudinal channel 22 and there are also other channels 23 and 24 in the top of the cross-bar extending transversely thereof. Each transverse channel 23 communicates at its ends with a space between a pair of adjacent lugs, while each transverse channel 24 extends directly across the cross-bar and across the tops of the channel 22. With this arrangement, it

' a pair of lugs 18 in registry on opposite sides of the cross-bar body. Each lug is also provided with an air channel 25 which extends across the lug from one side to the other. The bottoms of the various air channels have an inclination as follows:

There is a high point 26 in the longitudinal channel 22 at each intersection of the channel 22 with a transverse channel 24,.and the channel 24 slopes downwardly from the point 26 in each direction toward the outer ends of lugs 18. The channel 25, intersecting channel 24 and lying in the top of one lug, slopes downwardly in each direction .from the oint of intersection designated 27'. The

channel 23 slopes downwardly in each direction from its point of intersection 28 with will be observed that there is a high point in the channel 22 on the median line of each pair of lugs and low points in channel 22 where the channels. 22 and 23 intersect; Each channel 23 leads downwardly fromeach of the points 28 and the bottom ofchannel 23 at its outer end lies in substantially the same plane as the bottom of the channel 24 at each end of the latter.

Between adjacent cross-bars there is an air passage 29 for the upward flow of air from the ash pit to the fuel supported on top of the cross-bars. Since each cross-bar is of increasing thickness from bottom to top and each lug 18 is also of inrceasing cross-see there is atmospheric pressure in the ash-pan below the grate and a partial vacuum in the fire-box above the grate due to the draft, the

upper end of each passage constitutes an orifice at which a drop in pressure occurs. The point of maximum constriction of the passage is at the top of the cross-bar and the several channels 23, 24, and 25 communicate with the air passage below this point. Consequently each of these channels may be considered to constitute a minor orifice at which a pressure drop occurs. As a result, when the air drawn upward through the grate reaches the ends of the channels,itflows along the channels in a generally horizontal direction and thus is distributed to all parts of the under surface of the bed of fuel. Since the channels open into the passages below the point of maximum constriction thereof the further constriction of the passages above the channels offers resistance to the direct upward flow of the air which assists in changing its direction and causing its distribution in the manner described.

The channels lying in the fuel-supporting surface of the cross-bar and lugs sub-divide this-surface into a plurality of small fuelsupporting areas and air flows in contact with the metal on all sides of each area. The cooling effect of the air reduces the temperature of the metal and consequently prevents burning out of the fuel-supporting parts of the bar, and thus increases the life of the bar. The entire bed of fuel is supported on small separated surfaces, which together rep resent only a small fraction of the total area of air to all parts of the fuel bed. In actual practice, it has been found possible in a bar of the present construction to support the fuel properly on a multiplicity of these supporting surfaces which have an aggregate area amounting to approximately 12 per cent. of the total area of the grate bar. Consequently in this bar, the dead space is reduced far beyond that which occurs in grate bars of the construction heretofore employed, and the reduction of dead space is accomplished not only with the provision of proper support but in such a way as to provide a better air distribution. p

Each of the air channels in the top of the cross-bar and of the lugs has an upward inclination away from the air passage of adjacent cross-bars and this serves the useful purpose of assisting in the removal of the ash. Because of the excellent air distribution, fuel burned on a grate bar of the present construction is consumed to a fine ash which drops into the several air channels. The bottoms of these channels incline downwardly toward the air passages, and the ash slides down through the'channels to the passages and thence falls into the ash pan. This self-cleaning action is greatly facilitated when the cross-bar is mounted loosely on the supporting member in accordance with the Buckley invention, but also occurs in the case of a solid bar and particularly, when the latter is mounted in a frame structure subjected to frequent jarring, as, for instance,

tion from each of the channels to the fuel bed.

It will be observed that in a grate made up of the new bars, air can flow through each bar between adjacent cross-bars and airban also flow between the opposed ends of a pair of cross-bars on adjacent supporting members. Each cross-bar is generally of halfmoon shape, as shown more clearly in Fig. 1, so that the passage between the ends of adjacent cross-bars on different supporting members is also gradually constricted in a direction toward the fuel bed. Accordingly, throughout the grate made up of these new grate bars, air drawn up through the grate by the draft passes through orifices before it reaches the fuel and the pressure drop results in the desired horizontal flow of the air which insures wide distribution thereof to all parts of the fuel bed. With grate bars as -heretofore constructed, the air flowsdirectly up through air passages in the bars to the fuel bed and littleor no lateral flow in contact with the bottom of the fuel bed occurs. The air is accordingly delivered 'to the fuel in localized areas and there are many dead spaces in the fuel bed where'the combustion of fuel takes place in a sluggish manner. In the present grate bar, the dead spaces have been reduced to a minimum consistent with the proper support of the fuel, and in' addi tion the distribution of the air occurs in such a way as to cool the parts of the bar which actually support the fuel. Much better-combustion is thus obtained and the grate bar has a prolonged life.v

What I claim:

1. A grate bar comprising fuel Supporting means and provided with passages for air to the fuel supported by said means, said passages being of decreasingsize from bottom to top thereof and terminating in orifices at their upper ends, said fuel supporting means .being further provided with open top channels to sub-divide its upper portions into a multiplicity of small fuel-supporting sur-,

ported thereon, said passages being of increasing constriction from bottom to top of said members and terminating in orifices at their upper ends, and said members being provided with channels extending generally horizontally and sub-dividing said members into a plurality of small separated fuel-supporting areas, said channels communicating with said passages below the point of maximum constriction thereof and constituting minor ori-- ficcs at which occurs a pressure drop effective to promote horizontal flow of the air beneath the fuel bed.

3. A grate bar which includes a plurality of cross-bars disposed side by side in a row and spaced to provide passages for the upward flow of air between them, said cross-bars being formed to effect constriction of said passages, and a plurality of substantially horizontal air channels in the tops of said crossbars, said channels communicating with said passages below the point of maximum constriction of the passages.

4:. A grate bar which includes a plurality of cross-bars, the upper surfaces of which constitute a fuel support, said cross-bars beingspaced to provide passages for the upward flow of air between them to the fuel supported by the bars, said passages being gradually constricted from the bottom toward-the top, and air channels sub-dividing the fuel-supporting surface of each cross-bar and communicating with said air passages at a point below the maximum constriction thereof.

5. A grate bar which includes a plurality of cross-bars placed side by side, the top of each cross-bar providing a fuel-supporting surface, said cross-bars being spaced to provide passages for the upward flow of air between them, said passages being increasingly constricted from bottom to top thereof, and intersecting air channels in the top of each cross-bar sub-dividing the fuel supporting surface thereon, said air channels communicating with the air passages below the point of maximum constriction thereof and extending substantially horizonal with a slight upward inclination-away from said passa es.

6. K grate bar which includes a plurality of cross-bars disposed side by side, each crossbar having a series of spaced lugs on each side thereof, opposed sidcsof adjacent crossbars with their lugs defining air passages for the upward flow'of'air between them, said cross-bars and lugs being formed to effect gradual constriction of each passage from the lower-intake end to the upper discharge end thereof, the upper surfaces of each crossbar with its lugs serving to support the fuel, and air channels subdividing said surfaces and communicating with said passages below the point of maximum constriction thereof, each cross-bar having a longitudinal channel and spaced transverse channels com municating therewith.

7. A grate bar which includes a plurality of plate-like members disposed side by side in spaced relation, each member having a series of spaced lugson each side thereof, the lugs of the two series being oppositely disposed, said meinbers being spaced to provide passages for the upward flow of air between them, eachpassage being of decreasin cross-sectional area from the lower intaEe end thereof to the upper outlet end, the top of each member ith its lugs providing a fuel-supporting surface, andopen-top air channels sub-dividing said surface and communicating with said air passages below the outlet ends thereof, said members having a central longitudinal channel and spaced transverse channels, certain of the latter phannels extending over the tops of opposite ugs.

8. A grate bar comprising a longitudinal member and a plurality of cross-bars extending beyond said member laterally thereof,

each cross-bar having a plurality of lugs on each side face thereof and connecting air channels in'the upper faces of the cross-bar .and lugs, said cross-bars being 'of increasing thickness from bottom to to and being spaced to provide air passages o decreasing cross-section from bottom to top of the crossars, the channels communicating with the passages below the point of maximum con-' striction of said passages. i

9. A grate bar comprising a longitudinal member and a plurality of cross-bars extend-1 mg beyond said member laterally thereof,

one side thereof, said lugs extending down- Wardly from the top of the member and decreasing in size from their tops to their lower ends, adjacent lugs in part defining vertical air passages of increasing constriction upwardly, and open top air channels in the upper faces of the lugs and member, said channels communicating with the passages be low thepoint of maximum constriction of said passages.

In testimony whereof I aflix my signature.

. JAMES b. THOMPSON.

each ,cr'oss-bar being provided on each side face with a series of tapering lugs extending down from; the top surface of the cross-bar and of increasing cross-section from bottom to top, adjacent lugs in part defining an air passage of decreasing cross-sectional area ottom to top of said lugs, and air chan nels in the top-of the cross-bar and said lugs,

saidchannels communicating with said passages below the tion thereof.

10. In a grate bar, a fuel-supporting member havinga plurality of lugs on each side face thereof andconnec'ting air channels in point of maximum constric- 

